When several kinds of information are to be displayed on a cathode ray tube (CRT), a color display helps the operator categorize the information more easily than does a monochrome display. The conventional color shadow mask CRT includes red (R), green (G), and blue (B) phosphors on the back of the faceplate of the CRT. When one or more of these phosphors are irradiated by the electron guns of the CRT, many different colors can be rendered visible on the CRT. However, when using two or more beams to irradiate two or more color phosphors and thereby provide a combined color, the beams are sometimes misconverged. This misconvergence causes a reduction in the quality of the resolution of the display. in order to overcome this problem, these color CRTs are provided with convergence circuits for compensating for this misconvergence. The convergence circuits can be very complex and expensive. Consequently, the conventional color CRTs are not suitable for use with simple color displays, such as logic analyzer displays in which only a few different colors are required. Self-converged CRTs employing red, green and blue phosphors are known, but the amount of possible misconvergence of a display using more than one color is not tolerable.